Variable Rate for Variable Soils

In one pass across his field, Kentucky farmer Joel Armistead can find five to six soil types. That’s why he will be incorporating variable-rate speed control on his T-L Irrigation pivots in his largest field starting this spring. Of Armistead’s 1,500 acres, 200 are under irri­ga­tion. His corn needs more water on the red soil hills than in the bottomland. Since adding irrigation in 2008, Armistead Farms has raised its corn yields by an average of 100 bu. per acre. Now, he hopes to further reduce his fuel costs while becoming more effi­cient with water application.

First, Armistead will have Veris Technologies create a soil-type map of the field. He expects to spend between $3,000 and $3,500, in addition to the cost of an ordinary digital panel to equip his pivots with tele­metry and variable-rate irrigation (VRI) capabilities.

Since CropMetrics works with T-L to build water prescriptions and equip the pivot panel to follow those prescriptions, the setup for farmers is minimal, says Ken Moore, R&K Pivots, who is Armistead’s dealer.

Armistead pumps as much as 6" to 8" of irrigation water from a spring-fed river during the growing season, but that figure can drop significantly in a wet year. While he can do so without restrictions right now, Armistead says he is planning ahead for a time when water limits could be enacted. He also anticipates adding speed control to additional pivots on an adjoin­ing field once he has more data demonstrating the practice will help his bottom line.